Abstract
π-Conjugated polymers are a class of materials featuring an alternation of single and double bonds along their backbone, a configuration that can result in delocalized π-electrons. The unique electronic structure of these polymers makes them vital in applications such as organic electronics, solar cells and light-emitting diodes. A key feature in such materials is the emergence of topological quasiparticles, termed solitons, which are crucial for their observed high electrical conductivity. By using on-surface synthesis, we present a chemical reaction based on the regio- and stereoselective coupling of indenyl moieties for fabricating π-conjugated acenoindenylidene polymers, which feature a longitudinal polyacetylene backbone, on a Au(111) surface. The relationship between structural parity and electronic properties is investigated. We discover that odd-membered polymers exhibit an in-gap soliton state, which, due to their low bandgaps, spatially extends several nanometres along the longitudinal polyacetylene backbone. Our findings pave the way for the design of π-conjugated polymers that are able to host intrinsic solitons through chemical design by exploiting structural parity, without the need for external doping.
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Data availability
The datasets generated during and/or analysed during the current study are available at the IMDEA Nanoscience repository via https://repositorio.imdeananociencia.org/home.
Code availability
The Fireball software package is available at https://github.com/fireball-QMD and the PP-SPM software package can be downloaded at https://github.com/Probe-Particle/ppafm#probe-particle-model. FHi-aims code is a commercial package available upon request from the developers. The Amber code and the necessary postprocessing tools are available for non-commercial use at the website of the Amber project: https://ambermd.org/index.php.
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Acknowledgements
This project has received funding from MCIN/AEI/10.13039/501100011033 through grants PID2019-108532GB-I00, PID2022-139933NB-I00 and PID2022-140845OB-C62. We acknowledge support from the (MAD2D-CM)-IMDEA-Nanociencia project funded by Comunidad de Madrid, by the Recovery, Transformation and Resilience Plan, and by NextGenerationEU from the European Union. We thank support from the European Regional Development Fund of the European Union, from Xunta de Galicia (Centro de Investigación de Galicia accreditation 2019–2022, ED431G 2019/03) and Xunta de Galicia-Gain Oportunius Program. We appreciate funding from the CzechNanoLab Research Infrastructure supported by MEYS CR (LM2018110) and project GACR number 20-13692X. J.I.U. acknowledges the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement number 886314 and financial support from MCIU for the Ramón y Cajal program (RYC2022-037352-I). J.J. and B.A. thank the Agencia Estatal de Investigación for the award of predoctoral fellowships (PRE2020-092897 and BES-2017-079748, respectively). A.G. and A.B. acknowledge financial support from the Juan de la Cierva Program.
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J.I.U., P.J., D. Peña and D.E. conceived the project. D.E. coordinated the research efforts. K.B., A.B., O.S., A.P.S., K.L., J.M.G., R.M., J.I.U. and D.E. acquired and analysed the experimental data. A.G., M.L., D.S.-P. and P.J. performed the calculations. J.J., B.A., D. Pérez and D. Peña designed and synthesized the molecular precursor. K.B., J.I.U., P.J., D. Peña and D.E. wrote the manuscript with contributions from the other authors.
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Nature Synthesis thanks Ingmar Swart and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Primary Handling Editor: Alison Stoddart, in collaboration with the Nature Synthesis team.
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Unprocessed original STM, nc-AFM and simulated images in jpg format, for each corresponding Supplementary Figure.
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For each panel, unprocessed original STM and nc-AFM images in jpg format and txt files indicating the experimental parameters.
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For each panel, unprocessed original STM and nc-AFM images in jpg format and txt files indicating the experimental parameters.
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For each panel, unprocessed original STM and nc-AFM images in jpg format and txt files indicating the experimental parameters.
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Biswas, K., Janeiro, J., Gallardo, A. et al. Designing highly delocalized solitons by harnessing the structural parity of π-conjugated polymers. Nat. Synth 4, 233–242 (2025). https://doi.org/10.1038/s44160-024-00665-8
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DOI: https://doi.org/10.1038/s44160-024-00665-8
